Noiseless pile driver

ABSTRACT

A pile-driving apparatus in which the inertia of a reciprocated weight produces a force impulse at one end of each stroke which is applied to the head of a pile via an impact-enforcing mechanism which includes resilient means such as a cushion of air or oil, thereby driving the pile in a relatively quiet manner without the noise of hammer impacts.

United States Patent Takenosuke Ono Tokyo, Japan July 10, 1970 Oct. 12, 1971 North Engineering Co., Ltd.

Inventor Appl. No. Filed Patented Assignee NOISELESS PlLE DRIVER 7 Claims, 6 Drawing Figs.

173/116, 173/131, 173/139 Int. Cl E02d 7/00 Field of Search 173/116,

[56] References Cited UNITED STATES PATENTS 886,193 4/1908 Dewitt 173/131 1,029,102 6/1912 Cazin 173/131 3,406,524 10/1968 Blenkarn et a1 173/128 FOREIGN PATENTS 257,805 3/1913 Germany 173/131 Primary Examiner-James A. Leppink Attorney-Steinberg & Blake ABSTRACT: A pile-driving apparatus in which the inertia of a reciprocated weight produces a force impulse at one end of each stroke which is applied to the head of a pile via an impact-enforcing mechanism which includes resilient means such as a cushion of air or oil, thereby driving the pile in a relatively quiet manner without the noise of hammer impacts.

PATENTEflUcnann 3,612,188

sum; or 2 INVENTOR fA/(Emsm 04 0 BY M ATTORNEY$ NOISELESS PILE DRIVER FIELD'OF THE INVENTION The'present invention relates to apile driver which i's'capable of driving piles, for example, concrete or sheet 'piles for use in construction projectstintothegground withoutcausing-excessive noise.

BACKGROUND OFTIIEINVENTION ltis known that th'e'conventional pile-driver ingeneral utilizes a weightas a hammer, the weight being perpendicularl dropped on the head ofa-pile to effect the driving of thepile into the ground by percussion. ln'con'se'quence'noise caused by the percussion of the hammer striking the head of the pile continues throughoutthe pile-driving operation, and this isa greatpubli'c nuisance.

There have been various attempts to provide quiet pile drivers by obviating the noise of percussion. For instance there is a pile driver whichemploy's vibration, in which a' pair of rotary weights, arranged parallel and eccentrically supported by a shaft, are contained in a case which case is mounted'on the headofa pile. Said'pair'of weights are rotated in the same direction and this generates vibration in the vertical direction which presses thepile into the ground.

The above-described device has the advantage that it obviates the percussion noise since a hammer is not'used. The forces caused by the moving pair of weights will act upon the pile in the vertical direction. The downward movement may press the pile into the ground by a certain amount and the following upward movement will pull the pile upwardly. Thus by repeatedly pressing and pulling the pile by the upward and downward movement of the weight, the pile is gradually driven further into the ground. However, this mechanism has a defect in that the overall efficiency "ofthe pile-driving operation is reduced since the driving force of said downward impact is gradually decreased in correspondence with the in crease of the frictional resistance betwee'nthe pile and the circumjacent ground due to the vertical motion of the pile itself as it is pressed further into the ground.

An object of the present invention is to provide a quiet and efiicient piledriving apparatus.

SUMMARY OF THE INVENTION The invention provides pile-driving apparatus comprising a body including pile-engaging means, an impact-generating mechanism carried by said body and comprising a weight arranged for reciprocation towards and away from said pile-engaging means and means for reciprocating said weight, whereby in operation the impact-generating mechanism generates a pile-driving impulse from the inertia of the reciprocating weight when the weight reaches a dead point nearer the pileenga'ging means and impact-enforcing means including resilient means arranged to transmit said pile-driving impulse from the impact-generating mechanism to said body.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be more clearly understood from the following description of one embodiment, by way 'of example, with reference to the accompanying drawings in which:

FIG. I is a front view of a form of pile-driving apparatus according to the present invention,

FIG. 2 is a side view thereof,

FIG. 3 shows a cross section on the line III-Ill in Fig. 2,

FIG. 4 shows a cross section on the line lV-IV in Fig. 2,

FIG. 5 is an enlarged view in vertical cross section of part of Fig. 4, and

FIG. 6 is an illustration of the embodiment in use.

DESCRIPTION OF SPECIFIC EMBODIMENT As indicated in Fig. 6, in use, the apparatus includes a main body 4 which is suspended, for example, by wire 3, from the top of a tower 2 erected at the point of the pile-driving operation for a pile I.

Two main parts of the apparatus are an impact-generating mechanism'which enables 'a weight to reciprocate vertically, and impact-enforcing means located under said impactgenera'ting mechanism which transmits the pile-driving force generated by saidimpact-generating mechanism more effectively by utilizing the resilience of a fluid suchas air or oil'as a cushion for preventing the impact from'directlyacting onthe .pile head.

The body 4 comprises four columns 5 having equal length and connected with a top frame '6 and abottom'frame Tat the four corners of these frames. Referring to Fig. 4, a'shackle 10 with springsfl and '9 interposed between it and the top frame 6 is'secured atop the center'of the top frame 6. The apparatus maybe suspendedby a wire 3 by connecting the lower end of the wire to the shackle 10. A case 11 is located within the bottom frame 7. A chuck 1'3 for conn'ecting'the apparatus to the mounted in casing T5 for vertical reciprocation, and an electric motor 17 whichis fixed atop said casing 15.

Referring to FIG. 2, guide rollers 18 which contact two of said columns 5 are provided at the upper end and on one side of said casing 15 so as to enable the casing '15 to move vertically within themain body 4.

A crank shaft 19 extends through the casing I5 the bottom thereof. Apulley 20 provided at one end of the crank shaft 19 outside the casing I5, and a pulley 21 on the shaft of said motor 17, are connected by means of a belt 22 which makes contact with a biased tensioning pulley 23 at a predeterminedposition.

The weight 16 inside the casing 1 5 is vertically slidable along the guide ribs 24 (see FIG. 4), which project from the inner walls of the casing 15. Crank pin 25, which is provided at the center of the crank shaft 19 and the weight I6, are connected bymeans o'fa connecting'rod 26.

The impact-enforcing mechanism comprises a piston 28 (see FIGS. 4 and "5) in a cylinder 29 below the casing 15 and within the bottom frame 7 of the body 4. The piston 28 is connected to the bottom of the casing 15 at the center thereof by means of 'ball-and-socke't joint 30. The cylinder 29 is fixed in- 'side the case 11 in the bottom frame 7. Thus, the air or oil in the cylinder 29 will be kept pressurized when the socket 31 of the ball-and-socket joint 30 is inserted in the cylinder.

Piston 28 incorporates a one-way fluid flow arrangement which is now described.

As shown in FIGS. 4 and 5, the piston 28 is hollow inside, and is provided with apertures for entry of air (or oil) in the top thereof. A valve seat 34 having apertures 33 is provided at the center of the bottom of the piston A vertically slidable shaft 35 passes through the center of the valve seat 34. As spring 36 on the shafl 35 is arranged to bias the valve 37 at the bottom of the shaft 35 into contact with the valve seat. Bellows 38 are provided between the casing 15 and the bottom frame 7 for preventing entry of dust. The pile-driving apparatus as just described operates in the following manner. The wire 3, let out by a winch, is suspended from the upper end of the tower 2. The body 4 is suspended from the wire 3, and also connected to the head of the pile l by means of chuck 13. When the pile-driving apparatus is arranged in the abovedescribcd manner, the motor in the impact-generating mechanism is actuated to rotate the crank shaft 19 in the casing 15 by means of belt 22, whereupon the weight 16 reciprocates vertically within the casing 15.

The FIG. 4 illustrates the condition when the weight 16 reaches its lower dead point. The casing 15 will move upwards within the main body 4 as the weight 16 goes up to its upper dead point and when the weight 16 comes down from its upper dead point, the casing 15 then comes down driven by the inertia of the descending weight. Thus the reciprocal motion is repeated.

The casing 15 thus reciprocates as does the weight 116 due to the inertia of the vertically reciprocated weight which is located inside and linked to the casing. However, this reciprocal motion of the casing 15 will not greatly influence the main body 4 since the piston 28 attached to the casing will slide in the cylinder 29.

FIG. 5 illustrates the condition when the piston 28 in the cylinder 29 is rising, together with the casing 15. Piston 28 will naturally encounter some resistance from the internal pressure above the piston since the cylinder is airtight when the piston is ascending within the cylinder. However, since the piston 28 is provided with the apertures 32 and 33 at top and bottom, the air or oil present above the piston will enter into the piston through said apertures 32 and eventually press down the valve 37 against the biassing force of the spring 36 so that the air or oil can further flow through the bottom apertures 33. Thus the inside of the cylinder 29 is then in the state wherein the air or oil (or other medium) may freely flow, whereby the resistance against the rising of the piston 28 in the cylinder 29 will be greatly reduced.

As the weight 16 in the casing descends from the upper dead point to the lower dead point, the inertia of the weight 16 will be transformed into a downward force impulse on the cylinder 29, because there is then no substantial escape for the fluid beneath the descending piston 28. This will be transmitted to the head of the pile 1 which is connected to the bottom frame 7 of the main body 4. Since the weight will not touch the bottom surface of the casing 15 even when it reaches the lower dead point, no loud percussion noise will be generated though the downward force derived from the inertia of the descending weight is transferred to the pile.

Although the embodiment shown in the drawings is provided with the impact-enforcing mechanism 27 comprising cylinder 29 and piston 28, in a modified form this form of impact-enforcing mechanism is omitted. lnstead, the casing 15 as the impact-generating mechanism is suspended by wire or the like resilient member from the top frame 6 of the main body 4 while the head of the pile 1. is connected to the chuck 13 on the bottom frame 7 of the main body 4 as before. The force impulse derived from the descending weight 16 will then be transmitted to the main body 4, and hence to the pile, through the wire or like suspension of the casing 15, thereby driving the pile into the ground.

In the present invention, the impact-enforcing mechanism is provided on top of the said fundamental mechanism for pile driving to further enforce the percussion force generated by the impact-generating mechanism. That is, as has been described and shown in the drawings, when the casing 15 ascends due to the inertia attendant the ascension of the weight 16 of the impact-generating mechanism, the piston will go upward in the cylinder without any resistance. When the weight reaches its upper dead point, the valve 37 will be lifted by the resilience of the spring 36 to be tightly in contact with the seat valve 34, whereupon the aperture 33 is closed.

When the weight 16 starts to descend and the casing 15 accordingly descends by the inertia thereof, the air or oil present in the cylinder 29 will be pressurized by the piston as the valve 37 of the piston is in the closed state. As the weight 16 further descends, the pressure upon the air or oil will gradually increase in correspondence therewith. As the pressure reaches its maximum the piston 28 will halt at a position where it does not touch the bottom surface of the cylinder 29, being pressurized. The percussion force generated at the time when the weight reaches its lower dead point will be transmitted to the head of the pile 1 while the air or oil present in the cylinder is being pressurized by the piston. Since this pressure under the piston is developed from the inertia of the descending weight 16, it is quite abrupt instead of gradual in its nature. Thus, when the piston preasurizes the air or oil present in the cylinder to the maximum the pressure itself will act upon the pile as the pile-driving force.

As a result, the pile will receive both percussion impact generated at the lower dead point of the weight and when the pressure i n the iston is at the maximum.

The driving orce for the pile 1 rs thus In the form of a combination of said two forces. Functionally speaking, the percussion by the weight 16 is transmitted resiliently to the pile in the form of the pressure developed under the piston 28, and thereby the percussion impact will act upon the pile most effectively.

Since the piston is connected to the cylinder by means of a ball-and-socket joint, the piston can move in accurate alignment in the cylinder despite very slight rocking motion of the cylinder as it rises.

As can be understood from the foregoing description, the present invention is capable of generating a percussion impact without excessive accompanying noise such as occurs with conventional pile drivers, because the piston is prevented from striking the bottom of the cylinder by the pressure of the fluid under the piston. Moreover, since the driving force acting on the pile is very powerful as it is the compound force of the percussion of the weight and the pressure in the impactenforcing mechanism, the present invention offers the advantage of efficient and effective pile driving.

What is claimed is:

1. Pile-driving apparatus comprising a body, said body including pile-engaging means, an impact-generating mechanism, said impact-generating mechanism being carried by said body and said impact-generating mechanism compris' ing a weight supported for reciprocation towards and away from said pile-engaging means, the weight reaching a dead point when it is nearest the pile-engaging means, and means for reciprocating said weight, the impact-generating mechanism generating a pile-driving impulse from the inertia of the reciprocating weight when the weight reaches said dead point, and impact-enforcing means including resilient means for transmitting said pile-driving impulse from said impactgenerating mechanism to said body.

2. Apparatus according to claim 1 in which said resilient means comprises a fluid.

3. Apparatus according to claim 2 in which said impact-enforcing means includes a piston and cylinder arrangement, said piston and cylinder arrangement coupling said impactgenerating means to said body, said fluid being contained in said cylinder, and a one-way fluid flow arrangement permitting pressurization of the fluid by the piston only when said weight is moving towards said dead position.

4. Apparatus according to claim 1 wherein the impact-enforcing means is located between the impact-generating mechanism and the pile-engaging means.

5. Apparatus according to claim 1 wherein said impactgenerating mechanism is slidably mounted in said body, said impact-generating means being slidable in the direction of reciprocation of the weight.

6. Apparatus according to claim 1 wherein said body in- .cludes a frame, said frame being transverse to the direction of reciprocation of said weight, said pile-engaging means being connected to said frame and said impact-generating mechanism being coupled to said frame by means of said impact-enforcing means.

7. Apparatus according to claim 1 wherein said impactgenerating mechanism comprises a housing, said housing being coupled to said impact-enforcing means, said weight being contained in, and mounted for reciprocation relative to said housing, a motor, and a drive coupling, said drive coupling coupling said weight to said motor for reciprocating said weight. 

1. Pile-driving apparatus comprising a body, said body including pile-engaging means, an impact-generating mechanism, said impactgenerating mechanism being carried by said body and said impactgenerating mechanism comprising a weight supported for reciprocation towards and away from said pile-engaging means, the weight reaching a dead point when it is nearest the pile-engaging means, and means for reciprocating said weight, the impactgenerating mechanism generating a pile-driving impulse from the inertia of the reciprocating weight when the weight reaches said dead point, and impact-enforcing means including resilient means for transmitting said pile-driving impulse from said impactgenerating mechanism to said body.
 2. Apparatus according to claim 1 in which said resilient means comprises a fluid.
 3. Apparatus according to claim 2 in which said impact-enforcing means includes a piston and cylinder arrangement, said piston and cylinder arrangement coupling said impact-generating means to said body, said fluid being contained in said cylinder, and a one-way fluid flow arrangement permitting pressurization of the fluid by the piston only when said weight is moving towards said dead position.
 4. Apparatus according to claim 1 wherein the impact-enforcing means is located between the impact-generating mechanism and the pile-engaging means.
 5. Apparatus according to claim 1 wherein said impact-generating mechanism is slidably mounted in said body, said impact-generating means being slidable in the direction of reciprocation of the weight.
 6. Apparatus according to claim 1 wherein said body includes a frame, said frame being transverse to the direction of reciprocation of said weight, said pile-engaging means being connected to sAid frame and said impact-generating mechanism being coupled to said frame by means of said impact-enforcing means.
 7. Apparatus according to claim 1 wherein said impact-generating mechanism comprises a housing, said housing being coupled to said impact-enforcing means, said weight being contained in, and mounted for reciprocation relative to said housing, a motor, and a drive coupling, said drive coupling coupling said weight to said motor for reciprocating said weight. 